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The String Theory Landscape

Simons Center for Geometry and Physics, Stony Brook University, Stony Brook, NY 11794, USA
Universe 2019, 5(7), 176; https://doi.org/10.3390/universe5070176
Received: 11 June 2019 / Revised: 17 July 2019 / Accepted: 18 July 2019 / Published: 20 July 2019
(This article belongs to the Special Issue The Multiverse)
String/M theory is formulated in 10 and 11 space-time dimensions; in order to describe our universe, we must postulate that six or seven of the spatial dimensions form a small compact manifold. In 1985, Candelas et al. showed that by taking the extra dimensions to be a Calabi–Yau manifold, one could obtain the grand unified theories which had previously been postulated as extensions of the Standard Model of particle physics. Over the years since, many more such compactifications were found. In the early 2000s, progress in nonperturbative string theory enabled computing the approximate effective potential for many compactifications, and it was found that they have metastable local minima with small cosmological constant. Thus, string/M theory appears to have many vacuum configurations which could describe our universe. By combining results on these vacua with a measure factor derived using the theory of eternal inflation, one gets a theoretical framework which realizes earlier ideas about the multiverse, including the anthropic solution to the cosmological constant problem. We review these arguments and some of the criticisms, with their implications for the prediction of low energy supersymmetry and hidden matter sectors, as well as recent work on a variation on eternal inflation theory motivated by computational complexity considerations. View Full-Text
Keywords: string theory; quantum cosmology; string landscape string theory; quantum cosmology; string landscape
MDPI and ACS Style

Douglas, M.R. The String Theory Landscape. Universe 2019, 5, 176.

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